The present invention relates to novel benzoquinazoline thymidylate synthase inhibitors, to processes for preparing them and pharmaceutical formulations containing them. U.S. Pat. No. 4,814,335 discloses inter alia that compounds of the formula (0): 
wherein R is hydrogen, fluoro, nitro, optionally substituted amino, carboxy, azido, alkoxy, trimethylsulphonyl, trifluoromethylsulphonyl or alkoxycarbonyl have biological response-modifying activity, i.e. antiviral, antibacterial and anticancer activity. However, no specific examples of compounds of the formula (0) are provided.
Thymidylate synthase is an enzyme catalysing the terminal step in the de novo synthesis of thymidylate required for DNA synthesis. It has been postulated that inhibitors of this enzyme may be expected to have anti-tumour activity and it has been reported (Jones et al, J. Med. Chem. 1986, 29, 468) that the in-vivo antitumour activity of N10-propargyl-5,8-dideazafolic acid arises solely from its inhibitory effect on this enzyme.
It has now been found that a group of benzoquinazoline compounds are inhibitors of the enzyme thymidylate synthase and have antitumour activity.
Accordingly, the present invention provides compounds of the formula (I) 
or a salt thereof, wherein the dotted line represents a single or double bond,
R1 is C1-4 alkyl or amino optionally substituted by a C1-4 alkyl, C1-5 alkanoyl or benzyl group;
R2, R3, R4 and R5 are the same or different and each is selected from hydrogen, phenyl, halo, nitro,
a group S(O)nR8 wherein n is the integer 0, 1 or 2 and R8 is halo or is C1-4 alkyl or a group NR9R10 wherein R9 and R10 are both hydrogen,
a group NR11R12 wherein R11 and R12 are the same or different and each is hydrogen or C1-4 alkyl,
a group OR13 wherein R13 is hydrogen or C1-4 alkyl optionally substituted by halo;
a C1-4 aliphatic group optionally substituted by a group OR14 or NR14R15 wherein R14 and R15 are the same or different and each is hydrogen or C1-4 alkyl;
or two of R2 to R5 are linked together to form a benzo group,
or one of R2 to R5 is a group xe2x80x94Xxe2x80x94Yxe2x80x94R16 wherein X is CH2, NR17, CO or S(O)m and m is 0, 1 or 2 and R17 is hydrogen or a C1-4 aliphatic group and Y is CH2, NR17xe2x80x2, O, or S(O)m, wherein mxe2x80x2 is 0, 1 or 2 and R17xe2x80x2 is hydrogen or a C1-4 aliphatic group provided that X and Y are only the same when each is CH2, or xe2x80x94Xxe2x80x94Yxe2x80x94 is a group xe2x80x94Oxe2x80x94, xe2x80x94NR17xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94Nxe2x95x90Nxe2x80x94 wherein R17 is as hereinbefore defined, R16 is a C1-4 aliphatic group or a 5- or 6-membered aromatic ring optionally substituted by a group R18 at a position at least one carbon atom removed from that linked to Y, the 5- or 6-membered ring being optionally further substituted by a halo atom; and R18 is halo, C1-4 alkoxy, nitro, nitrile, C1-4 alkyl optionally substituted by halo, halo or a group COR19 wherein R19 is hydroxy, C1-4 alkoxy or C1-6 alkyl optionally substituted by one or two carboxyl groups or C1-12 esters thereof or R19 is a group NR20R21 wherein R20 and R21 are the same or different and each is hydrogen or C1-4 alkyl optionally substituted by hydroxy or R19 is an amino acid group or an ester thereof in which the first nitrogen atom of the amino acid group may be linked to the 5- or 6-membered aromatic ring to form a further 5- or 6-membered heterocyclic ring or R19 is an C2-3 alkylene group linked to the 5- or 6-membered aromatic ring to form a further 5- or 6-membered ring;
R6 and R7 are the same or different and each is C1-4 alkyl optionally substituted by hydroxy or C1-4 alkoxy or together form a benzo group;
provided that at least one of R2 to R7 is other than hydrogen and that R4 is not methoxy when R1 is hydroxy or methyl.
By the term halo is meant fluoro, bromo, chloro and iodo.
By the term C1-4 aliphatic group is meant a C1-4 alkyl, alkenyl, or alkynyl group.
By the term amino acid group is meant naturally occurring amino acids.
Preferred amino acid groups include glycine, glutamic acid and polyglutamic and groups.
When the amino acid group is linked to the 5- or 6-membered aromatic ring, this is via a carbon atom of the aromatic ring adjacent to carbon to which COR19 is attached.
Preferably the dotted line is a double bond.
Suitable substituents for the aromatic ring R16 include halo, C1-4 alkyl and C1-4 alkoxy each optionally substituted by one to five halo atoms. Most suitably there are one or two substituents selected from fluoro, chloro, methyl, trifluoromethyl and methoxy, and preferably fluoro, or no substituents on the aromatic ring. In one preferred embodiment, xe2x80x94Xxe2x80x94Yxe2x80x94R16 is a group 
wherein R18 is as hereinbefore defined and preferably a group COR19 as hereinbefore defined and R22 is hydrogen or fluoro.
In a further preferred embodiment Xxe2x80x94Yxe2x80x94R16 is a group 
wherein H2NR19a is a glutamic or polyglutamic acid group and Z is CH2, S or O.
Suitably, R1 is an amino group optionally substituted by one or two methyl or ethyl groups or R1 is a methyl or ethyl group. Preferably R1 is an amino or methyl group.
Suitably, at most only three, and preferably at most only two, of R2 to R5 are other than hydrogen and each is independently selected from hydrogen, halo, hydroxy, nitro, C1-3 alkyl optionally substituted by hydroxy or C1-2 alkoxy, C1-3 alkoxy, amino optionally substituted by one or two methyl or ethyl groups, or a group S(O)nR23 wherein n is 0, 1 or 2 and R23 is a C1-4 alkyl group or an amino group optionally substituted by one or two methyl or ethyl groups, or one of R2 to R5 is a group xe2x80x94Xxe2x80x94Yxe2x80x94R24 where R24 is a group 
wherein R18, R19a, R22 and Z are as hereinbefore defined. In one preferred embodiment R18 is nitro or a group 
wherein R25, R26 and R27 are the same or different and each is hydrogen or a C1-4 alkyl group and t is an integer from 0 to 6. Preferably R25, R26 and R27 are hydrogen and t is 0. Preferably Z is CH2 or S.
Preferably one of R2 to R5 is a group xe2x80x94Xxe2x80x94Yxe2x80x94R24 as hereinbefore defined. Preferably R3 is a group xe2x80x94Xxe2x80x94Yxe2x80x94R24.
Suitably R6 and R7 are the same or different and each is hydrogen, methyl, ethyl or methyl substituted by bromo, hydroxy or methoxy. Preferably R7 is hydrogen and R6 is methyl.
Preferably xe2x80x94Xxe2x80x94Yxe2x80x94 is a group xe2x80x94SO2NR17xe2x80x94 or CH2NR17 wherein R17 is as hereinbefore defined.
Suitably R17 is hydrogen or a C1-4 alkyl or alkenyl group and preferably R17 is hydrogen or methyl.
One group of compounds of the present invention is that of the formula (Ia) 
or a salt thereof, wherein the dotted line represents a single or double bond, R1a is C1-4 alkyl or amino optionally substituted by a C1-4 alkyl, C1-5 alkanoyl or benzyl group; R2a, R3a, R4a and R5a are the same or different and each is selected from hydrogen, halo, nitro, a group S(O)nR8a wherein n is the integer 0, 1 or 2 and R8a is halo or is a C1-4 alkyl or amino group; a group NR11aR12a wherein R1a and R12a are the same or different and each is hydrogen or C1-4 alkyl, a group OR13a wherein R13a is hydrogen or C1-4 alkyl optionally substituted by halo, a C1-4 aliphatic group optionally substituted by a group OR14a or NR14aR15a wherein R14a and R15a are the same or different and each is hydrogen or C1-4 alkyl, or one of R2a to R5a is a group xe2x80x94Xxe2x80x94Yxe2x80x94R wherein X is CH2, NR17a, CO or S(O)m and m is 0, 1 or 2 and R17a is hydrogen or a C1-4 aliphatic group and Y is CH2, NR17xe2x80x2a, O, or S(O)mxe2x80x2 wherein mxe2x80x2 is 0, 1 or 2 and R17xe2x80x2a is hydrogen or a C1-4 aliphatic group provided that X and Y are only the same when each is CH2, or xe2x80x94Xxe2x80x94Yxe2x80x94 is a group xe2x80x94NR17a, xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94Nxe2x95x90Nxe2x80x94 wherein R17a is as hereinbefore defined, R16a is a C1-4 aliphatic group or an optionally substituted 5- or 6-membered aromatic ring substituted by a group R18a at a position at least one carbon atom removed from that linked to Y and R18a is nitro, nitrile, C1-4 alkyl optionally substituted by halo, halo or a group COR19a wherein R19a is C1-6 alkyl optionally substituted by one or two carboxyl groups or C1-4 alkoxy, a group CONR20aR21a wherein R20a and R21a are the same or different and each is hydrogen or C1-4 alkyl or R19a is a glutamic or polyglutamic acid group or an ester thereof in which the first nitrogen atom of the glutamic or polyglutamic acid group may be linked to the 5- or 6-membered aromatic ring to form a further 5- or 6-membered heterocyclic ring; R6a and R7a are the same or different and each is C1-4 alkyl optionally substituted by hydroxy or C1-4 alkoxy or together form a benzo group, provided that at least one of R2a to R7a is other than hydrogen and that R4a is not methoxy when R1a is hydroxy or methyl.
A further group of compounds of the present invention is that of the formula (II) 
or a salt thereof, wherein R1, R6, R7 and the dotted line are as hereinbefore defined and R28 to R31 are the same or different and each is selected from hydrogen, halo, nitro, a group S(O)nR8, a group NR11R12, a group OR13, or a C1-4 aliphatic group optionally substituted by a group OR14 or NR14R15 wherein R8, R11, R12, R13, R14 and R15 are as hereinbefore defined, provided that R28 to R31 are not all hydrogen and that R30 is not methoxy wherein R1 is hydroxy or methyl.
A preferred group of compounds of the present invention is that of the formula (III): 
or a salt thereof, wherein R1, R6 and R7 are as hereinbefore defined and R32 to R35 are the same or different and one is a group Xxe2x80x94Yxe2x80x94R16 and the others are the same or different and each is selected from hydrogen, halo, nitro, a group S(O)nR8, a group NR11R12, a group OR13 or a C1-4 aliphatic group optionally substituted by a group OR14 or NR14R15, wherein X, Y, R8, R11, R12, R13, R14, R15 and R16 are as hereinbefore defined.
A further preferred group of compounds of the present invention is that of the formula (IV): 
wherein R1, R6, R7 and R32 to R32 are as hereinbefore defined.
Preferably R33 is a group Xxe2x80x94Yxe2x80x94R16 as hereinbefore defined.
Preferred compounds of the formula (I) include:
3-Amino-9-bromobenzo[f]quinazolin-1(2H)-one
3-Amino-9-ethynylbenzo[f]quinazolin-1(2H)-one
N-(4-((3-Amino-1,2,5,6-tetrahydro-1-oxobenzo[f]quinazolin-9-yl)sulfonamido)benzoyl)-L-glutamic acid
N-(4-((1,2,5,6-tetrahydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)-sulfonamido)benzoyl)-L-glutamic acid
N-(4-((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)sulfonamido)-benzoyl)-L-glutamic acid
N-(4-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)-2-fluorobenzoyl)-L-glutamic acid
N-(4(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)benzoyl)-L-glumatic acid
(S)-2-(5-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)-amino-1-oxo-2-isoindolinyl)glutamic acid
9-((4-Acetylanilino)methyl)-3-methylbenzo[f]quinazolin-1(2H)-one
3-Methyl-9-((4-nitroanilino)methyl)benzo[f]quinazolin-1(2H)-one
N-(4-(((3-Amino-1,2-dihydro-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)benzoyl)-L-glutamic acid
3-Amino-9-((4-nitroanilino)methyl)benzo[f]quinazolin-1(2H)-one
9-((4-Acetylanilino)methyl)-3-aminobenzo[f]quinazolin-1(2H)-one
(RS)-2-(2-(4-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)phenyl)-2-oxoethyl)glutaric acid
Ethyl-4-(4-(((1,2-dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)phenyl)-4-oxobutyrate
4-(4-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)phenyl)-4-oxobutyric acid
N-(4-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)-2-fluorobenzoyl)glycine
Ethyl N-(4-(((1,2-Dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl)amino)-2-fluorobenzoyl)glycinate
Certain compounds of the formula (I) contain asymmetric carbon atoms and are, therefore, capable of existing as optical isomers. The individual isomers and mixtures of these are included within the scope of the present invention.
Salts of the compounds of the present invention may comprise acid addition salts derived from an amino group or anionic species derived from a compound of formula (I), for example when this is substituted by a carboxy group, and a cation. In both types of salts, the therapeutic activity resides in the moiety derived from the compound of the invention as defined herein and the identity of the other component is of less importance although for therapeutic and prophylactic purposes it is, preferably, pharmaceutically acceptable to the patient. Examples of pharmaceutically acceptable acid addition salts include those derived from mineral acids, such as hydrochloric, hydrobromic, phosphoric, metaphosphoric, nitric and sulphuric acids, and organic acids, such as tartaric, acetic, trifluoroacetic, citric, malic, lactic, fumaric, benzoic, glycollic, gluconic, succinic and methanesulphonic and arylsulphonic, for example p-toluenesulphonic, acids. Examples of salts comprising an anionic species derived from a compound of formula (I) and a cation include ammonium salts, alkali metal salts, such as sodium and potassium salts, alkaline earth salts, such as magnesium and calcium salts, and salts formed with organic bases, for example, amino salts derived from mono-, di- or tri-(lower alkyl) or (lower alkanol)amines, such as triethanolamine and diethylamino-ethylamine, and salts with heterocyclic amines such as piperidine, pyridine, piperazine and morpholine. The pharmaceutically acceptable salts together with the salts which are not thus acceptable have utility in the isolation and/or the purification of the compounds of the invention, and the pharmaceutically unacceptable salts are also useful in being convertible to the pharmaceutically acceptable salts by techniques well known in the art.
Esters of compounds of the formula (I), formed from compounds of the formula (I) which contain a carboxy group are often useful intermediates in the preparation of the parent acid.
The present invention also provides a process for the preparation of compounds of the formula (I) which comprises a method well known to those skilled in the art, for example:
(i) when it is required to prepare a compound of the formula (I) wherein the dotted line represents a single bond, the reaction of a compound of the formula (V) 
wherein R2 to R5 are as hereinbefore defined and R36 is a C1-4 alkyl group, with a compound 
wherein R1 is as hereinbefore defined. This reaction is suitably carried out in a polar solvent, for example a C1-4 alkanol or glycol, conveniently methanol or ethanol, normally in the presence of a base, for example a metal alkoxide conveniently formed from the metal and the solvent, i.e. sodium methoxide or ethoxide, at an elevated temperature, for example 50xc2x0 to 150xc2x0 C. and conveniently 60xc2x0 to 90xc2x0 C. The compound of the formula 
is conveniently liberated in situ from a salt form, for example the hydrochloride or carbonate salt, by the base which is preferably present in the reaction mixture. This reaction is a preferred method for preparing those compounds of the formula (I) wherein one of R2 to R5 is not a group XYR16.
(ii) the direct insertion of a substituent R2, R3, R4 or R5 into the aromatic ring system. This is particularly suitable for the insertion of halo or nitro substituents or a group SO2hal. This is carried out by methods conventionally employed to insert these substituents on aromatic ring systems, for example in the case of a bromo substituent: reaction of the corresponding compound where R2 to R7 are all hydrogen with bromine in a suitable solvent such as glacial acetic acid at a temperature between 20xc2x0 and 100xc2x0 C., conveniently between 50xc2x0 and 70xc2x0 C.; in the case of a substituent SO2hal: reaction of the corresponding compound where R2 to R7 are all hydrogen with a halosulphonic acid at a temperature between xe2x88x925xc2x0 and 100xc2x0 C., conveniently between 20xc2x0 and 30xc2x0 C.; in the case of a nitro substituent: reaction of the corresponding compound where R2 to R7 are hydrogen with nitric acid or potassium nitrate in sulphuric acid at xe2x88x9230xc2x0 to 50xc2x0 C. and conveniently at xe2x88x925xc2x0 to 5xc2x0 C. The position of attachment of the substituent to the aromatic ring system may be effected by, inter alia, the nature of the substituent R1. Thus, when R1 is an amino group an SO2 group will be attached to the 8-position but when R1 is a methyl group an SO2 group will be attached to the 9-position.
(iii) the hydrolysis of a compound of the formula (VI) 
wherein R1 to R7 are as hereinbefore defined. This hydrolysis is conveniently carried out by acid, for example a mineral acid such as hydrochloric acid, at a temperature of between 20xc2x0 and 120xc2x0 C. and conveniently at between 60xc2x0 and 100xc2x0 C.
(iv) the conversion of one compound of the formula (I) to a further compound of the formula (I), for example:
(a) the dehydrogenation of a compound of the formula (VII): 
wherein R1 to R7 are as hereinbefore defined and R37 is C1-4 alkyl or a primary, secondary or tertiary amino group within the definition of R1 or when it is desired to prepare a compound of the formula (I) wherein R1 is a primary amino or a hydroxy group R37 is a protected amino or hydroxy group; and thereafter removing the protecting group where appropriate. This dehydrogenation is conveniently carried out by (i) bromination of the 5- or 6-position of the compound of the formula (VII) by a reagent such as N-bromosuccinimide followed by dehydrobromination (ii) catalytic dehydrogenation in inert solvent (e.g. diglyme), (iii) dehydrogenation with DDQ. Reaction (i) is conveniently carried out in the presence of a base, such as pyridine, in a inert solvent, for example benzene, at a non-extreme temperature, for example between 0 and 80xc2x0 C. The pivaloyl group is a suitable protecting group when R1 is NH2.
The compounds of the formula (VII) are conveniently prepared from the corresponding compounds of the formula (V) as described in method (i) above.
(b) when it is desired to prepare a compound of the formula (I) wherein one of R2 to R5 is a group S(O)mYR16 wherein Y and R16 are as hereinbefore defined, the reaction of the analogous precursor substituted by the group SO2hal with a compound HYR16 wherein hal is halo and R16 is as hereinbefore defined. Suitably this reaction is carried out in a basic medium, for example pyridine, at an elevated temperature, i.e. 25 to 175xc2x0 C. The precursor is prepared by analogy to method (ii) above whereby a compound of formula (I) or (II), wherein at least one of R2-R5 is H in the position desired for substitution, is reacted with chlorosulfonic acid at xe2x88x925 to 100xc2x0 C.
(c) when it is desired to prepare a compound of the formula (I) substituted by an amino group the reduction of the corresponding compound substituted by a nitro group. Reduction is suitably carried out by hydrogenation in the presence of a transition metal catalyst for example palladium on charcoal in an inert solvent, for example an alkanol, such as ethanol, at a non-extreme temperature, for example (25 to 35xc2x0 C.).
(d) when it is desired to prepare a compound of the formula (I) substituted by a hydroxy group, the removal of an alkyl group from the corresponding alkoxy compound. This reaction is conveniently carried out in the presence of a strong acid, such as hydrobromic acid at a non-extreme temperature.
(e) when there is more than one substituent R2 to R5, removal of one of the substituents, for example removal of bromine by catalytic debromination, such as hydrogenation in the presence of a transition metal catalyst, conveniently palladium on charcoal, in a polar solvent such as a C1-4 alkanol at between 0xc2x0 and 50xc2x0 C. conveniently 20xc2x0 to 30xc2x0 C.
(f) when one of R2 to R5 is an alkyl group, the halogenation of this alkyl group, for example bromination by N-bromo-succinimide in an inert solvent, such as benzene, at a temperature between 20xc2x0 and 120xc2x0 C., conveniently 70xc2x0 to 90xc2x0 C.
(g) the displacement of a leaving group from a substituent R2 to R5 by another group, for example conversion of a haloalkyl group to an hydroxyalkyl or alkoxyalkyl group by reaction with an alkali metal hydroxide or alkoxide respectively in alkanol, at a temperature between 20xc2x0 and 120xc2x0 C.; or conversion of a group CH2hal wherein hal is halo to a group CH2YR16 by reaction with a compound HYR16 wherein Y and R16 are as hereinbefore defined, for example N-(4-aminobenzoyl)-L-glutamic acid diethyl ester, ethyl N-(4-amino-2-fluorobenzoyl)glycinate or 4-fluoroanilino, in a dipolar aprotic solvent, such as dimethylformamide, at a non-extreme temperature, for example 25xc2x0 to 160xc2x0 C. and conveniently 95xc2x0 to 105xc2x0 C. optionally followed by the addition of a weak base such as sodium or patassium carbonate or bicarbonate.
(h) the replacement of one substituent R2 to R5 by another substituent R2 to R5, for example displacement of bromo by an alkynyl moiety which is preferably protected by a trialkylsilyl group in the presence of a suitable catalyst, such as palladium acetate. The trialkylsilyl group may then be removed by base catalysed hydrolysis, for example with potassium carbonate. The alkynyl group can be reduced, by catalytic hydrogenation, to an alkenyl or alkyl group.
When R1 is an amino group, it is often convenient to carry out these conversions with the amino group protected, for example with a pivaloyl group.
The compounds of the formula (V) may be prepared by the reaction of a dialkyl carbonate with a compound of the formula (VIII) 
wherein R2 to R5 are as hereinbefore defined in the presence of a base, conveniently sodium hydride. This reaction is analogous to that described by J. Vebrel and R. Carrie (Bull. Soc. Chim. Fr., 1982, 161).
The compounds of the formula (VI) wherein R1=NH2 may be prepared by the reaction of dicyandiamide with a compound of the formula (VIII). This reaction is described by Rosowsky et al (J. Heterocyclic Chem. 9, 263 (1972).
The compounds of the formula (VIII) may be prepared by methods well known to those skilled in the art, for example by methods analogous to those described by J. Vebrel and R. Carrie (Bull. Soc. Chim. Fr., 1982, 161) and J. H. Burkhalter and J. R. Campbell (J. Org. Chem., 26, 4332 (1961) and those outlined in Schemes 1, 2 and 3 appended hereto.
The present invention also relates to novel chemical intermediates of the formula (VI). Compounds of the formula (VI) possess pharmocological properties and may therefore be useful in their own right as well as being useful intermediates in the preparation of compounds of the formula (I).
Whilst it is possible for the compounds or salts of the present invention to be administered as the raw chemical, it is preferred to present them in the form of a pharmaceutical formulation. Accordingly, the present invention further provides a pharmaceutical formulation, for medicinal application, which comprises a compound of the present invention or a pharmaceutically acceptable salt thereof, as hereinbefore defined, and a pharmaceutically acceptable carrier therefor.
The pharmaceutical formulation may optionally contain other therapeutic agents that may usefully be employed in conjunction with the compound or salt of the present invention, for example a pyrimidine nucleoside transport inhibitor that is capable of enhancing the antineoplastic activity of the compounds and salts of the present invention. The expression xe2x80x9cpharmaceutically acceptablexe2x80x9d as used herein in relation to the carrier is used in the sense of being compatible with the compound or salt of the invention employed in the formulation and with any other therapeutic agent that may be present, and not being detrimental to the recipient thereof. The carrier itself may constitute one or more excipients conventionally used in the art of pharmacy that enable the compound or salt of the present invention and any other therapeutic agent that may be present, to be formulated as a pharmaceutical formulation.
The pharmaceutical formulations of the present invention include those suitable for oral, parenteral (including subcutaneous, intradermal, intramuscular and intravenous) and rectal administration although the most suitable route will probably depend upon, for example, the condition and identity of the recipient. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. All methods include the step of bringing into association the active ingredient, i.e., the compound or salt of the present invention, with the carrier. In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredient with a liquid carrier or, a finely divided solid carrier or both, and then, if necessary, forming the associated mixture into the desired formulation.
The pharmaceutical formulations of the present invention suitable for oral administration may be presented as discrete units, such as a capsule, cachet, tablet, or lozenge, each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid such as a syrup, elixir or a draught, or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion. The formulation may also be a bolus, electuary or paste.
Generally, a tablet is the most convenient pharmaceutical formulation suitable for oral administration. A tablet may be made by compressing or moulding the active ingredient with the pharmaceutically acceptable carrier. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form, such as a powder or granules, in admixture with, for example, a binding agent, an inert diluent, a lubricating agent, a disintegrating agent and/or a surface active agent. Moulded tablets may be prepared by moulding in a suitable machine a mixture of the powdered active ingredient moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient.
The pharmaceutical formulations of the present invention suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain, for example, an anti-oxidant, a buffer, a bacteriostat and a solution which renders the composition isotonic with the blood of the recipient, and aqueous and non-aqueous sterile suspensions which may contain, for example, a suspending agent and a thickening agent. The formulations may be presented in uni-dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injection, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
The pharmaceutical formulations of the present invention suitable for rectal administration may be presented as a suppository containing, for example, cocoa butter and polyethylene glycol.
As mentioned hereinbefore, compounds and salts of formula (I) have anti-neoplastic activity as demonstrated hereinafter in the human colon SW480 adenocarcinoma cell culture cytotoxicity tests in which representative compounds of the present invention have been shown to be active. Compounds and salts of formula (I) also have anti-neoplastic activity as determined hereinafter in the human breast MCF7 adenocarcinoma cell culture cytotoxicity tests. It has thus been established that compounds of the present invention are able to inhibit neoplastic growth. Therefore, compounds and salts of the present invention are of use in medicine and in particular in the treatment of neoplastic growth, including solid tumours such as melanoma, breast and colon tumours in mammals. Accordingly, the present invention yet further provides a method for the treatment of susceptible malignant tumours and leukemia in an animal, e.g., a mammal, which comprises administering to the animal a therapeutically effective amount of a compound or salt of the present invention. In the alternative, there is also provided a compound or salt of the present invention for use in medicine and in particular for use in the treatment of a neoplastic growth, e.g., malignant tumours.
The present invention also provides the use of a compound of formula (I) or a salt thereof for the manufacture of a medicament for the treatment of neoplastic growth.
The animal requiring treatment with a compound or salt of the present invention is usually a mammal, such as a human being.
Particular examples of a neoplastic growth requiring treatment include malignant tumours.
Compounds and salts of the formula (I) also inhibit the enzyme Thymidylate Synthase from E. coli and Candida Albicans. Therefore, compounds and salts of the present invention may be of use in the treatment of bacterial and fungal infections in mammals.
The route by which the compound or salt of the present invention is administered to the animal may be oral, topical, parenteral (including subcutaneous, intradermal, intramuscular, intravenous or rectal). If the compound or salt is presented in the form of a pharmaceutical formulation, which, as mentioned hereinbefore, is preferred, then the actual formulation employed will of course depend on the route of administration elected by the physician or veterinarian. For example, if oral administration is preferred, then the pharmaceutical formulation employed is, preferably, one which is suitable for such a route.
A therapeutically effective amount of a compound or salt of the present invention will depend upon a number of factors including, for example, the age and weight of the animal, the precise condition requiring treatment and its severity, the nature of the formulation, and the route of administration, and will ultimately be at the discretion of the attendant physician or veterinarian. However, an effective amount of a compound of the present invention for the treatment of neoplastic growth, for example colon or breast carcinoma will generally be in the range of 0.1 to 100 mg/kg body weight of recipient (mammal) per day and more usually in the range of 1 to 10 mg/kg body weight per day. Thus, for a 70 kg adult mammal, the actual amount per day would usually be from 70 to 700 mg and this amount may be given in a single dose per day or more usually in a number (such as two, three, four, five or six) of sub-doses per day such that the total daily dose is the same. An effective amount of a salt of the present invention may be determined as a proportion of the effective amount of the compound par se.
An effective amount of a compound of the present invention for the treatment of disorders of the immune system (e.g. rheumatoid arthritis and tissue rejection) and related diseases such as psoriasis, will generally be in the range of 0.07-10 mg/kg body weight of recipient (mammal) per day. Thus for a 70 kg adult human, the actual amount per day would usually be from about 5-700 mg per day and this amount may be given in a single dose per day, or more usually dosing would be intermittent e.g. at 12 hourly intervals or weekly. An effective amount of a salt of the present invention may be determined as a proportion of the effective amount of the compound per se.
The treatment of neoplastic growth with a compound of the present invention may at times require the administration to the animal of an antidote or rescue agent, e.g. thymidine.